The (apparently disrotatory) thermal ring opening of 4-nitro-1-cyclobuten-1 -amines
作者:Peter J. S. S. van Eijk、Cor Overkempe、Willem P. Trompenaars、David N. Reinhoudt、Sybolt Harkema
DOI:10.1002/recl.19881070203
日期:——
and ynamines 2. Heating of 3a-d yielded products corresponding with disrotatory ring opening viz. the 1,3-dienes 6a-d. Heating of 3e,f at 60°C gave the dienes 7a,b, as the result of a conrotatory ring opening reaction, together with the trans-2-nitrocyclobutenes 8a,b, as the result of a hydrogen shift in the cyclobutene ring. Upon prolonged heating at 80°C 8b was converted into the diene 7b. Treatment
从硝基(环)烯烃1和乙胺2的热(2 + 2)环加成反应中分离出一系列4-硝基-1-环丁烯-1-胺3。加热3a-d产生对应于旋转环开口的产物。1,3-二烯6a-d。由于旋转开环反应的结果,在60℃加热3e,f得到二烯7a,b,以及由于环丁烯环中的氢转移而导致的反式-2-硝基环丁烯8a,b。在80℃下长时间加热后,8b转化为二烯7b。用酸处理3e得到2-硝基环丁烯9a和9b。通过X射线分析阐明了3a,3f,6a和7b的结构。6a-d的形成归因于产物的E / Z异构化,最初是通过旋转的开环形成的。